import cv2
img = cv2.imread('yihun.jpg')
b = img[:, :, 0]
g = img[:, :, 1]
r= img[:, :, 2]
m1 = cv2.merge((b, g, r))
m2 = cv2.merge((r, g, b))
m3 = cv2.merge((g, b, r))
cv2.imshow('m1', m1)
cv2.waitKey()

cv2.imshow('m2', m2)
cv2.waitKey()

cv2.imshow('m3', m3)
cv2.waitKey()
